Improvement in scroll-sawing machines



r. n. SMITIL SCROLL-SAWING MACHINE. No.170,456. Patented Nov.30,,1875.

N. PETERS, PNOTO-LITHOGRAFHER, WASHINGTON, D C.

UNITED STATES PATENT OFFICE.

FRED. D. SMITH, OF DAVENPORT, IOWA.

IMPROVEMENT IN SCROLL-SAWING MACHINES.

. v Specification forming part of Letters Patent No. 170,456, dated November 30, 1875; application filed May 11, 1875.

To all whom it may concern Be it known that I, FRED. D. SMITH, of Davenport, Iowa, have invented an Improvement in Scroll-Sawing Machines, of which the following is a specification:

The nature of my invention relates to the kind of sawing-machines as invented by me, and secured by Letters Patent No. 109,351, November 15, 1870 and its object is to form, instead of a double toggle-jointed set of levers, avtriplc toggle-jointed combination of levers, as a direct connection between the walkingbeam P and the treadle T, in this way reducing the angle of deflection of the levers, and thereby increasing the power of the machine, which, in the double toggle-jointed-lever combination, could not be obtained without reducing the stroke of the saw, and therefore presented serious imperfections.

The machine is fully illustrated in the accompanying drawings, in Which- Figure l is a side view of themachine; Fig. 2, a plan View of the same, with'the working table B and the Walking-beams P and P and their supports S removed. I

A represents the frame of the machine, made of cast-iron; S, an ordinary support to carry the two walking-beams Pand P ,which are connected at their rear ends by means of a stirrup, Z. The front ends of the Walking-beams P and P receive the saw-blade in the usual manner, the upper walking-beam P being provided with an eccentric lever to clamp the saw and stretch it tight. (1 d are two bearings, in which revolvesthe crank-shaft m m, with the crank G at its center, on each side of which are fastened on the shaft the two fiy-wheels F and F. On. the end of the crank-shaft m is attached a pulley, P, in case that the machine should be driven by power. T is a treadle, swinging around a shaft, 0. To this treadle T is fastened firmly, by means of the braces f and f,

the lower lever L, to which latter attaches the one end of a connecting-rod, 0, extending from the crank O on the lever L, provision having been made to adjust the length of the stroke by changing the point of connection of the connecting-rod 0. n is a'rocking lever. having its fulcrum at r, and being pivoted with its other end at about the middle of a second lever, L the lower end of which hinges to the upper free end of the lower lever L. The upper end of the second lever L hinges to a third lever, L and the free upper end of this latter attaches to the lower walking-beam P.

It will be evident that the combination of.

the three levers L, L and L requires only half of the amount of throw of the connectingrod for the same amount of stroke of the saw than the application of only two levers; but with the reduction of the travel of the conmeeting-rod 0 the angle of deflection that the swinging levers L, L, and L form with the position, where they are in a straight line, must necessarily be also reduced at the same rate, and the smaller this angle is the greater will be the power that is exerted by the levers L, L and L Another feature that gives this machine such a power is the direct connection in a straight line between treadle and saw by means of the levers L, L and L What I claim as new, and desire to secure by Letters Patent, is'

The application of toggle-jointed levers L,

L and L in combination with the rocking lever n, treadle T, connecting-rod o, and crankshaft m, substantially as and for the purpose set forth in the above specification.

FRED. D. SMITH. Witnesses:

W. OTTO GRoNEU,

. OHAs. E. SILsBEE. 

